BARRE — The associate director of Norwich University’s School of Business and Management has been found guilty of drunken driving.

Stephen M. Pomeroy, 57, of Northfield, was convicted in a jury trial in Washington County criminal court in Barre of one count of driving under the influence. Jury deliberations lasted about 30 minutes. Pomeroy, a retired Marine colonel, was ordered to pay a $400 fine.

Norwich University declined to comment for this story, with a representative saying the college does not comment on the personal lives of its employees. The school’s website lists Pomeroy as associate director and lecturer, with a specialization in leadership studies.

According to the Vermont State Police affidavit, a trooper was driving on Brook Road in Warren in March when he saw a vehicle quickly approaching him from behind. The trooper said he clocked Pomeroy driving 55 mph in a 40 mph zone and pulled him over.

State police say that as Pomeroy was looking for his registration, the trooper noted Pomeroy’s speech was slurred, his eyes were watery and a moderate odor of intoxicants was coming from the vehicle. When the trooper asked Pomeroy how many drinks he had consumed, state police say, Pomeroy replied, “a couple of beers.”

Pomeroy was then asked to perform field sobriety tests. State police say he had a hard time following directions and was unable to maintain his balance during the tests.

Pomeroy was then taken to the Middlesex barracks and processed for driving under the influence. A breath test showed he had a blood alcohol content of 0.102 percent a little over an hour after he was pulled over. The legal limit for driving in the state is 0.08 percent.

It was that breath test that was the basis for Pomeroy’s unsuccessful defense.

His attorney, Robert Kaplan, said in his closing argument that he hoped the jury was “a little bit frightened now” that it had heard how the state prosecutes charges of driving under the influence.

Earlier in the trial, Kaplan had questioned state forensic chemist Rebecca Mead about how the machine that analyzes a driver’s breath, the Datamaster DMT, functioned. In part, Mead explained the software the machine uses is patented and as such, she could not give a definite answer as to how the machine converts the numbers it reads into the breath test numbers it displays. Kaplan characterized that as the process being “secret.”

Kaplan also took issue with the standards the Department of Public Safety uses when analyzing how quickly alcohol leaves a person’s body.

After a breath test, the state uses an equation based on the rate alcohol leaves an average person’s body to calculate what the suspect’s blood alcohol content was when driving. Kaplan repeatedly asked Mead how the state comes up with that average person’s number, saying it’s based on some “mythical” person and not the actual rate that alcohol leaves Pomeroy’s system.

Mead said the standard has been established based on numerous studies conducted on alcohol’s effect on the body.

In her closing argument, Deputy State’s Attorney Kristin Wood said the case was “pretty straightforward” given the evidence. The jury agreed.